AM62x Temperature and Power Environmental Stresstesting Results¶

The MitySOM-AM62 SOM (6254-TX-DAD-TI) was placed in the MitySOM-AM62 Development Kit and loaded into the environmental chamber with the following configuration:

1. Industrial Temperature micro-SD used for boot media and reference filesystem
2. Industrial Temperature USB stick loaded into one of the USB 2.0 HUB positions
3. External USB connection made to PC (MitySOM-AM62 USB 2.0 Dual Role port configured as an RNDIS network device)
4. Both ethernet ports connected to an internal network at 1 Gbps link rates.
5. Micro-USB console port connected to external PC for console monitoring.
6. Monitor (1920x1080p) connected to HDMI port.

Stress Test software was enabled on the MitySOM-AM62 to perform the following operations (continuously) during test:

1. Running the "memtest" application on 256 MB of DDR4 memory
2. Running nandtest continuously on the MitySOM-AM62 OSPI NOR partitions
3. Running stress-drive tests on a USB stick partition.
4. Running stress-drive tests on a MitySOM-AM62 eMMC device partition.
5. Running stress-drive tests on a micro-SD card partition.
6. Running the TI provided 3D walking man OpenGL graphics program
7. Running a stats collection script which gathers CPU temperature, power / current draw, and CPU utilization
8. Running iperf on eth0
9. Running iperf on eth1
10. Running iperf on usb0, configured as an RNDIS network device

Note: the OLDI interface was not run during this test. Running the OLDI interface will draw additional power in order to drive the LVDS output links.

The system was allowed to run while the environmental chamber ranged from -45C to +65C, including soaks at each end of the range.

The figures below show the temperature of the AM62x (die temperature as reported by the kernel software), the chamber, the computed temperature rise, and the power consumed by the SOM.

Stress Testing with passive heat sink attachment¶

As shown in the above results, when operating under relatively heavy load with the development kit, there is an approximate 35C rise in CPU die temperature over ambient temperature above 50C. The rise exceeds the maximum specified junction temperature of the processor (105C for industrial grade parts) when the ambient environment reaches approximately 70C. The testing was repeated with one unit using an off-the-shelf (ATS-52170B-C1-R0) passive heat sink attached to the processor. Results are included in the figures below. The overall CPU rise dropped to between 22-27C, which should allow ambient operation at up to approximately 78-80C. Under heavy loads, additional thermal management (e.g., a fan, or a larger heat sink, etc.) will be required.

Idle Testing with passive heat sink attachment¶

In this case, the same heat sink was attached as previously mentioned and the system was booted to Linux and no additional software was run (beyond the data logging software) while the chamber was ramped from +20 to +85C. The CPU governor selected was "on-demand", and the typical operating frequency selected was in the range of 200-400 MHz. From the figures, the power consumption of the SOM is much lower, and the unit was able to run at temperatures up to 85C ambient (though, just barely within the CPU 105C limit).

CPU Max Frequency vs. CPU temperature¶

Measurements where taken while running a stresstest and using cpu fan heatsinks FJ23 23mm BGA 5V Fansink with stick-on-pad.

The following tests were conducted using five 6254-TX-X9D-RI SOMs.

Ambient = 85C

CPU Max Frequency (Hz)	SOM0 CPU temp (C)	SOM1 CPU temp (C)	SOM2 CPU temp (C)	SOM3 CPU temp (C)	SOM4 CPU temp (C)
1400000	108.8	102.7	104.8	102.1	103.8
1250000	102.1	98.4	100.3	97.5	99.8
1000000	101.4	98.2	99.9	97.2	99.1
800000	101	97	99	96.1	98.4
600000	100	96.5	98.2	95.9	97.3
400000	99.4	95.7	97.5	95.8	97
200000	97.7	94.5	97	94.5	95.7

echo <maxFreq> > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq

Additional heat sinks¶

Type	Model	Size	Idle Cpu Temp @ 65C Amb	Stress Cpu Temp @ 65C Amb
None	None		90C	99C
Passive	ATS-52170B-C1-R0	17mm X 17mm X 7.5mm	78C	90C
Passive	ATS_52150B-C1-R0	15mm X 15mm X 7.5mm	85C	93C
Passive	Alum Heatsink for Raspberry PI	15mm X 15mm X 15mm	83C	94C
Active	FJ23 23mm BGA 5V Fansink with stick-on-pad	23mm X 23mm X 21mm	80C	87C